Flexor digitorum profundus avulsion generally occurs at the tendon's insertion at the distal phalanx. The injured finger cannot actively be flexed at the distal interphalangeal joint. Radiographs are needed to exclude a concomitant avulsion fracture of the distal phalanx. Treatment is with surgery.
The injury most often occurs in American football and other contact sports (eg, rugby) when a flexed finger is forcefully extended (1). The fourth digit is the most commonly injured.
(See also Mallet Finger.)
General reference
1. Ruchelsman DE, Christoforou D, Wasserman B, et al. Avulsion injuries of the flexor digitorum profundus tendon. J Am Acad Orthop Surg. 2011;19(3):152-162. doi:10.5435/00124635-201103000-00004
Etiology of FDP Avulsion
Flexion of the hand digits is controlled by the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS). The FDP inserts on the distal phalanx and flexes the distal interphalangeal (DIP) joint.
The most classical mechanism of FDP injury is that an athlete grips the jersey or shirt of a second athlete, catching the flexed finger, which gets extended forcefully as the second athlete suddenly moves away, rupturing the tendon.
Flexor digitorum profundus tendon rupture can avulse a bone fragment.
Symptoms and Signs of FDP Avulsion
The injured athlete cannot actively flex the distal interphalangeal (DIP) joint. Palpation of the volar/palmar surface of the fingertip is painful. The affected finger rests in slight extension.
Diagnosis of FDP Avulsion
History and physical examination
Radiograph
Radiographs are needed to exclude an avulsion fracture of the distal phalanx. Active flexion of the affected distal interphalangeal (DIP) joint must be tested or the diagnosis can be easily missed.
Pearls & Pitfalls
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Treatment of FDP Avulsion
Surgery
The treatment of choice is prompt surgical repair performed by a hand specialist.
Key Points
Flexor digitorum profundus avulsion (FDP, also known as jersey finger) occurs in contact sports such as American football and rugby.
To avoid missing the injury, test active distal interphalangeal (DIP) joint flexion of the involved finger.
Refer affected patients to a hand specialist for surgical repair.
